Lifting equipment, such as cranes or winches, are often in situations where a load must be delivered to a location which is moving relative to the load or the lifting equipment. Exemplary situations include transferring a load from a ship to the seabed, transferring a load from a ship to a floating platform, transferring a load from a ship to a dock, transferring a load from a dock to a ship, transferring a load from a ship to a ship, transferring a load from a floating platform to a ship, and the like.
The relative motion of the load with respect to the destination is problematic, as it is unpredictable and can result in unwanted collisions or snapping of the load line. This can cause damage to the load if placed in a more violent manner than intended, or if the load is collided with water surfaces. In other instances, sudden buoying of the load when lowered into water can cause unwanted snapping of the load line, or other undesirable resonant effects. Similarly, a load being lifted that snags, or is otherwise encumbered, can cause a structural overload in the lifting apparatus.
Often, heave compensation systems, whether active or passive, are utilized to correct for such relative motion. Exemplary active systems in use include electric winch systems, hydraulic winch systems, and cylinder compensation. An exemplary passive system can be a soft spring.
Present systems are complex and require considerable space. Expensive components are required to determine required heave compensation, as well as to implement the heave compensation.
A need exists for a compact, cost-effective and space saving heave compensation system which can provide both passive and active heave compensation as necessary. A further need exists for a simple system with fewer failure modes than existing systems.
The present disclosure meets these needs.
The embodiments of the present disclosure are detailed below with reference to the listed Figures.